Offered as a foundation for subsequent analysis, this report presents data on the frequency of teacher turnover in New York State districts from 1972 to 1977 and discusses the methods used for calculations from State Department of Education records. Data drawn from a 1-in-20 random sample totalling 13,000 teachers are analyzed in order to investigate three types of turnover: quits, or transfer of teachers between districts; transfers of teachers between schools in the same district; and changes in teacher assignment. Figures cited in an introductory literature review are used to check the validity of New York turnover rates. The following section provides turnover rates for the time periods 1972-76 and 1976-77, analyzed in terms of teaching experience, age of teachers, and changes in district enrollment. The final section concludes that such factors as declining enrollment and seniority rules may determine teacher mobility and thus district staff composition, and that the turnover rates for New York do not differ significantly from teacher behavior in other states. Information on constructing the data set and on calculations of transfers and quits is appended. (MJL)